Many production and manufacturing operations use an assembly-line process wherein the product or article is sequentially moved in a steplike manner between adjacent working stations. These assembly-line processes utilize various types of conveyor systems for accomplishing the intermittent steplike movement of the product. While many different types of conveyor systems are commonly utilized, such as powered accumulating-type roller conveyors, chain conveyors and the like, nevertheless many of the conventionally utilized conveyor systems possess various disadvantages when considered for use under some assembly-line conditions. For example, many of the known conveyor systems are structurally and operationally complex, and hence expensive to purchase and maintain. Other conveyor systems are undesirable as to their space requirements, such as by requiring a large structural frame so that the conveyor bed is hence at an undesirably high elevation, or requiring either overhead or below-floor level supports which thus make initial installation and assembly of the conveyor extremely difficult and at the same time prevent efficient movement and/or modification of the conveyor system.
To improve upon the conveyor systems presently being utilized, specifically the complex powered accumulating-type roller conveyors which utilize complex drive mechanisms and elaborate controls and stop mechanisms to provide various zones, there has been developed an accumulating-type conveyor commonly referred to as an oscillating or reciprocating live-roller conveyor. In this type conveyor, the conveyor rolls for supporting the products are freely rotatably supported on a horizontally elongated frame, the latter being rollingly supported on a support floor or surface. A reciprocating drive, such as a fluid pressure cylinder, causes the conveyor to reciprocate or oscillate back and forth through a limited linear stroke. An elongated stationary frame extends longitudinally of the conveyor and mounts thereon movable dogs, normally weight- or spring-urged into the path of movement of the products. During the forward advance of the conveyor, the products are moved forwardly and pass by the dogs, which dogs engage and hold the products during the retraction of the conveyor. In this manner, the products are moved forwardly in an intermittent steplike manner. Conveyor systems of this type have proven desirable in that they permit a product or load to be advanced in a simple manner, and in fact the products can be readily accumulated on the conveyor in abutting relationship with one another while at the same time the driving force between the live conveyor rolls and the products is extremely small so that the line pressure developed between and along the accumulated products can thus be maintained at an extremely small magnitude. Examples of conveyor systems of this type are U.S. Pat. No. 4,037,714 (Koepke), U.S. Pat. No. 2,820,542 (Oswald) and U.S.S.R. Pat. No. 398 470.
While these oscillating live-roller conveyor systems do possess an advantageous mode of operation, nevertheless these known conveyor systems, such as illustrated by the above-identified patents, possessed structural and operational features which have severely limited their use and adaptation, or restricted their ease and/or flexibility of use. For example, these known conveyor systems have permitted products or loads to be moved therealong solely in a single direction, which directionalization of the complex and extensive conveyor system thus severely hampers and often prevents maximum utilization of the conveyor system when conveying of articles therealong in the opposite direction is desired. A directional reversal in these known conveyors can be accomplished (if at all) only by disassembling and reassembling the conveyors so as to be oppositely directed. This is obviously an extremely laborious and time-consuming task, and in many installations such reassembling of the conveyor so as to change the directionalization of same is not possible.
Another disadvantage with these known oscillating live-roller conveyors is the difficulty in causing the conveyed loads to be temporarily stopped at a desired location, such as at a work station, to permit the desired assembly or other operational steps to be carried out on the conveyed products. At the present time, this stoppage of loads can normally be accomplished only by providing a separate power-activated stop mechanism which an operator manually controls for stopping the selected load to permit the desired work steps to be carried out. Thus, these known oscillating live-roller conveyor systems have possessed disadvantages which have greatly restricted their flexibility and adaptability of use in many assembly-line production processes.
Still another common disadvantage of these known conveyor systems is their inability to efficiently utilize the maximum forward stroke of the conveyor, that is, their inability to maximize the forward steplike advance of the load. Since the conveyor is reciprocated forwardly through a preselected stroke, most of these conveyors have the dogs spaced at intervals which are slightly less than the conveyor stroke so as to insure that the load fully passes by the dog, which in turn normally permits a slight rearward movement of the load prior to its engaging the dog, and hence maximum conveying efficiency of the conveyor is not achieved.
Accordingly, the present invention relates to an improved oscillating accumulating-type live-roller conveyor system which overcomes the above-mentioned disadvantages as associated with known conveyors of this type. For example, the improved oscillating live-roller conveyor system of this invention utilizes swingable dogs or paddles which can be easily rotated so as to be directed in either direction, whereupon the directionalization of the conveyor system can be readily reversed in a simple and time-saving manner without requiring any structural rebuilding or reassembly of the conveyor system. Further, These dogs or paddles are preferably swingably mounted on the loads, such as skids or pallets, whereby maximum conveying efficiency is achieved inasmuch as the skid will hence move throughout the full forward stroke of the conveyor inasmuch as the dog travels along with the skid, thereby preventing any rearward movement of the skid during retraction of the conveyor. In fact, the conveyor system of this invention has been observed to result in the skid travelling through a stepwise distance which exceeds the conveyor stroke inasmuch as this arrangement enables the momentum of the skid to be utilized so as to maximize the steplike forward advance. In addition, the dogs or paddles are provided in cooperating pairs which are spaced sidewardly of the conveyor, such as by being positioned on opposite sides of the skid, whereupon when accumulating or stoppage of skids is desired, one of the dogs adjacent one side of the conveyor can be manually rotated so as to point in the upstream direction, with the other dog remaining in its downstream direction, whereupon the load can thus be maintained stationary even as the conveyor oscillates back and forth. Accumulating or stopping of loads can thus be carried out in a very simple and time-saving manner at any random location along the conveyor without requiring any additional stop mechanisms or controls.
In a preferred embodiment of the conveyor system according to this invention, a pair of elongated oscillating live-roller conveyor sections are disposed in side-by-side parallel relationship between a pair of horizontal guide rails, which guide rails project upwardly a slight distance above the roller surface of the conveyor rollers, whereby pallets or skids as conveyed along the conveyor sections are slidably guided unidirectionally along the conveyor between the guide rails. A pair of one-way holding mechanisms are mounted on opposite sides of the skid and cooperate with the upper surfaces of the guide rails for causing the skid to be unidirectionally stepped along the conveyor system as the conveyor sections reciprocate back and forth. The one-way holding mechanism includes an elongated dog or paddle which is swingably mounted on the side of the skid and has a lower edge which slides along the top surface of the guide rail during forward advance of the skid, and grippingly engages the top surface of the guide rail during retraction of the conveyor so as to prevent retraction of the skid. The paddle is urged, by its own weight, downwardly toward a pendant position, which causes the lower edge to engage the guide rail, with the paddle being maintained at a slight angle relative to the vertical so that the paddle is thus directed rearwardly of the conveyor. The paddles as mounted on opposite sides of the skid can be readily manually swung through the better part of a full revolution so that the paddles can be reversely directed relative to the longitudinal direction of the conveyor, whereupon the skids can be readily unidirectionally stepped along the conveyor in the opposite direction is desired. In addition, if stopping or accumulating of the skid is desired, then the paddle adjacent only one side of the conveyor is manually swung so as to be directed upstream, with the paddle on the other side of the skid remaining in a downstream direction, thereby holding the skid stationary even though the conveyor sections continue to oscillate back and forth. The skid is preferably provided with a shroud which is positioned directly adjacent and overlaps the top surface of the guide rail in surrounding relationship to the lower edge of the paddle to prevent an operator's foot from being accidentally trapped between the paddle and the guide rail.
Other objects and purposes of the invention will be apparent to persons familiar with systems of this general type upon reading the following specification and inspecting the accompanying drawings.